KR102695611B1 - Manufacturing method of starch using rice washing water - Google Patents

Abstract

The present invention relates to a method for manufacturing starch using rice washing water, and more specifically, the method comprises a starch recovery step of recovering starch from rice washing water, a distilled water mixing step of mixing distilled water with the starch recovered through the starch recovery step, a succinic acid mixing step of mixing anhydrous octenyl succinic acid and sodium hydroxide with the mixture prepared through the distilled water mixing step, a neutralization step of neutralizing the mixture prepared through the succinic acid mixing step, a centrifugation step of centrifuging the mixture neutralized through the neutralization step, and a washing and drying step of washing the starch separated through the centrifugation step and then drying it with hot air.
The method for manufacturing starch through the above process provides starch with significantly improved emulsification stability and freeze-thaw stability.

Description

MANUFACTURING METHOD OF STARCH USING RICE WASHING WATER

The present invention relates to a method for producing starch using rice washing water, and more specifically, to a method for producing starch using rice washing water which provides starch having significantly improved emulsification stability and freeze-thaw stability.

Due to social changes such as the recent increase in single-person households and changes in eating habits, the annual rice consumption per person per day is on the decline, but the demand for HMR products using rice as a raw material and processed rice foods for meal replacement and snack purposes is increasing (Korea Agro-Fisheries & Food Trade Corporation. 2021).

Rice-processed foods require a rice-washing process during the manufacturing process, and the rice-washing water generated during this process has high chemical and biological oxygen demand, which causes water pollution and incurs costs for its treatment. The Ministry of Environment (2021) announced that according to the results of a survey on wastewater discharge businesses by industry in 2019, the food and beverage industry ranked fourth in that order, followed by transportation and car washing, metal processing, petrochemicals, and food and beverage. The food and beverage industry had the highest BOD generation load of 551,000 kg per day, and the BOD emission load was the second highest at 2,700 kg per day.

In addition, the rice washing water generated during the rice processing process contains 0.32% of total solids and 0.11% of soluble solids, which corresponds to 1.65% of the total rice used and 0.6% of soluble solids when calculated as the loss per unit of rice usage (Shin DH 1997). The rice washing water contains nutrients beneficial to the human body, such as vitamin B group, lipids, and starch, and Kim MJ et al. (2011) reported that during the rice washing process, some of the nutrients of the rice move to the washing water, and the rice washing water contains about 0.7% of solid components such as carbohydrates, fat, and protein, and when dried, it contained 40.9% of carbohydrates, 22.9% of protein, and 19.6% of lipids, and the results of electron microscope observation showed that the starch particle shape was not damaged.

Rice washing water, which contains a large amount of beneficial ingredients, is a recyclable resource, but it is known as a source of pollution in domestic wastewater, so it is being discarded at a high cost. Only a portion of the discarded water is used as raw materials for feed, cosmetics, and medicines, so there have been attempts to apply a fermentation process to expand the recycling area and develop it into a functional material (Cho JI et al. 2004, Kim MJ et al. 2011, Lee D 2014), and there have been studies to recover effective ingredients such as proteins (Chung KY & Park SH 2002,). However, little research has been conducted on starch, which is contained in large amounts in washing water, to date.

Meanwhile, starch is a component that stores glucose produced by plants through photosynthesis in the form of particles in each part of the plant, and is also used as a natural food or as a material during the processing process or as an additive to maintain quality. In particular, modified starch is manufactured and used by modifying starch through physicochemical and enzymatic methods to have new properties depending on the use (Shin MS et al. 2021). Among them, octenyl succinate starch (OSA starch) is a chemically modified starch that esterifies starch and octenyl succinic acid (OSA) under alkaline conditions. The hydrophobic OSA group is combined with the hydrophilic structure of raw starch to convert it into starch with bipolarity, thereby lowering the interfacial tension between water and oil in the emulsion and contributing to emulsion stabilization (Nilsson L & Bergenstahl B 2006, Nilsson L & Bergenstahl B 2007).

In the present invention, in order to utilize rice washing water as a food additive material, powder and starch were separated from washing water, and the characteristics were compared with the starch separated from rice grains, and octenyl succinate starch was manufactured to examine the possibility of utilization as a food additive material such as a modified starch and an emulsifier and stabilizer. In addition, in order to diversify the characteristics of octenyl succinate starch, annealing treatment was performed in parallel to confirm the emulsification stability and freeze-thaw stability, and the possibility of utilization as an emulsifier and improvement of freeze-thaw stability by adding it to dumpling skin dough for steamed dumplings was examined.

Korean Patent Registration No. 10-1461639 (2014.11.07.) Korean Patent Registration No. 10-1848840 (April 9, 2018)

The purpose of the present invention is to provide a method for producing starch using rice washing water, which can produce starch having significantly improved emulsion stability and freeze-thaw stability.

The object of the present invention is achieved by providing a method for manufacturing starch using rice washing water, characterized in that the method comprises a starch recovery step of recovering starch from rice washing water, a distilled water mixing step of mixing distilled water with the starch recovered through the starch recovery step, a succinic acid mixing step of mixing anhydrous octenyl succinic acid and sodium hydroxide with the mixture prepared through the distilled water mixing step, a neutralization step of neutralizing the mixture prepared through the succinic acid mixing step, a centrifugation step of centrifuging the mixture neutralized through the neutralization step, and a washing and drying step of washing the starch separated through the centrifugation step and then drying it with hot air.

According to a preferred feature of the present invention, an annealing step of annealing the mixture prepared through the distilled water mixing step is further performed between the distilled water mixing step and the succinic acid mixing step, and the annealing step is performed at a temperature of 40 to 50°C for 20 to 30 hours.

According to a more preferred feature of the present invention, the starch recovery step is performed by centrifuging rice washing water, recovering a precipitate, purifying the recovered precipitate with a sodium hydroxide aqueous solution having a mass concentration of 0.2%, neutralizing it with a 1 N hydrochloric acid solution, washing it, and drying it.

According to a more preferred feature of the present invention, the distilled water mixing step is performed by mixing 180 to 300 parts by weight of distilled water with 100 parts by weight of starch manufactured through the starch recovery step.

According to a further preferred feature of the present invention, the succinic acid mixing step is performed by mixing 2 to 4 parts by weight of anhydrous octenyl succinic acid relative to 100 parts by weight of starch contained in the mixture prepared through the distilled water mixing step, mixing sodium hydroxide, and reacting the mixture for 5 to 7 hours while maintaining the pH of the mixture at 8 to 9.

According to a further preferred feature of the present invention, the neutralization step is performed by mixing 1N hydrochloric acid into the mixture prepared through the succinic acid mixing step to adjust the pH of the mixture to 6.9 to 7.1.

According to a further preferred feature of the present invention, the centrifugation step is performed at a speed of 4500 to 5500 rpm for 8 to 12 minutes.

The method for producing starch using rice washing water according to the present invention exhibits an excellent effect of producing starch with significantly improved emulsification stability and freeze-thaw stability.

Figure 1 is a flow chart showing a method for manufacturing starch using rice washing water according to one embodiment of the present invention.
Figure 2 is a flow chart showing a method for manufacturing starch using rice washing water according to another embodiment of the present invention.
Figure 3 is a photograph showing the appearance of starch manufactured through Examples 1 to 4.
Figure 4 is a graph showing the viscosity of an emulsion manufactured from annealed OSA starch and annealed OSA starch manufactured from washed water powder and washed water starch.
Figure 5 is a graph showing the results of measuring the cold-thaw stability of dumpling skins for steamed dumplings containing washing water powder and OSA starch.

Hereinafter, preferred embodiments of the present invention and the properties of each component will be described in detail. However, this is intended to be a detailed description to enable a person having ordinary skill in the art to which the present invention pertains to easily carry out the invention, and does not mean that the technical idea and scope of the present invention are limited thereby.

The method for manufacturing starch using rice washing water according to the present invention comprises a starch recovery step (S101) of recovering starch from rice washing water, a distilled water mixing step (S103) of mixing distilled water with the starch recovered through the starch recovery step (S101), a succinic acid mixing step (S105) of mixing anhydrous octenyl succinic acid and sodium hydroxide with the mixture prepared through the distilled water mixing step (S103), a neutralization step (S107) of neutralizing the mixture prepared through the succinic acid mixing step (S105), a centrifugation step (S109) of centrifuging the mixture neutralized through the neutralization step (S107), and a washing and drying step (S111) of washing the starch separated through the centrifugation step (S109) and then drying it with hot air.

The above starch recovery step (S101) is a step for recovering starch from rice washing water. The rice washing water is manufactured by pouring twice as much water into white rice and washing it twice.

The white rice grains washed in the above process were ground with a 0.2% sodium hydroxide solution and the starch was separated using an alkaline steeping method, and named white rice refined starch.

The above recovery of starch can be accomplished by vacuum concentrating rice washing water at a temperature of 35°C, centrifuging the resulting solution, and drying the precipitate at room temperature to produce concentrated washing water powder, or by centrifuging the rice washing water without a concentration process, then drying the precipitate at room temperature to produce precipitate powder, or by centrifuging the rice washing water, recovering the precipitate, purifying the recovered precipitate with a sodium hydroxide aqueous solution having a mass concentration of 0.2%, neutralizing it with a 1 N hydrochloric acid solution, washing it, and drying it, but the use of the last method is most preferable.

The above distilled water mixing step (S103) is a step of mixing distilled water with the starch recovered through the starch recovery step (S101), and is performed by mixing 180 to 300 parts by weight of distilled water with 100 parts by weight of the starch manufactured through the starch recovery step (S101).

In the above distilled water mixing step (S103), if the mixing amount of distilled water is less than 180 parts by weight or exceeds 300 parts by weight, the efficiency of the starch manufacturing process is reduced.

The above succinic acid mixing step (S105) is a step of mixing anhydrous octenyl succinic anhydride (OSA) and sodium hydroxide with the mixture prepared through the distilled water mixing step (S103). The step comprises mixing 2 to 4 parts by weight of anhydrous octenyl succinic anhydride relative to 100 parts by weight of starch contained in the mixture prepared through the distilled water mixing step (S103), mixing in sodium hydroxide, and reacting the mixture for 5 to 7 hours while maintaining the pH of the mixture at 8 to 9.

The starch manufactured by the above process through the succinic acid reaction has significantly improved emulsion stability and freeze-thaw stability.

The neutralization step (S107) above is a step of neutralizing the mixture manufactured through the succinic acid mixing step (S105), and is performed by mixing 1N hydrochloric acid into the mixture manufactured through the succinic acid mixing step (S105) to adjust the pH of the mixture to 6.9 to 7.1.

Through the above process, the starch contained in the neutralized mixture can be neutralized and used as starch for food additives.

The above centrifugation step (S109) is a step of centrifuging the mixture neutralized through the neutralization step (S107), and is comprised of a process of putting the mixture neutralized through the neutralization step (S107) into a centrifuge and centrifuging it at a speed of 4,500 to 5,500 rpm for 8 to 12 minutes.

Through the above process, starch can be separated from the mixture, but if the speed of the centrifugation step (S109) is less than 4,500 rpm or the centrifugation time is less than 8 minutes, the yield of separated starch is low, and if the speed of the centrifugation step (S109) exceeds 5,500 rpm or the centrifugation time exceeds 12 minutes, energy is unnecessarily wasted, which is not desirable.

The above washing and drying step (S111) is a step of washing the starch separated through the centrifugation step (S109) and then drying it with hot air. The step is comprised of washing the starch separated through the centrifugation step (S109) with distilled water to remove foreign substances, and then drying it using hot air at 50 to 70°C.

In addition, an annealing step (S104) of annealing the mixture manufactured through the distilled water mixing step (S103) may be further performed between the distilled water mixing step (S103) and the succinic acid mixing step (S105), and it is preferable that the annealing step (S104) be performed at a temperature of 40 to 50°C for 20 to 30 hours.

By performing an annealing process at the above temperature and time, starch with improved emulsion stability and freeze-thaw stability is provided.

Hereinafter, a method for manufacturing starch using rice washing water according to the present invention and the properties of starch manufactured by the method will be described with examples.

<Example 1> Production of refined white rice starch

Washed white rice grains were ground with a 0.2% mass concentration sodium hydroxide aqueous solution and starch was separated using an alkaline steeping method to produce refined white rice starch.

<Example 2> Production of green powder for washing water

After washing white rice twice with twice the amount of water, the water used for washing was collected to produce rice washing water. The rice washing water was vacuum concentrated at 35°C, centrifuged, and the precipitate was dried at room temperature to produce concentrated washing water powder.

<Example 3> Production of precipitated powder from washing water

After washing the white rice twice with twice the amount of water, the water used for washing was collected to produce rice washing water. The rice washing water was centrifuged and the sediment was dried at room temperature to produce washing water precipitate powder.

<Example 4> Production of purified starch from washing water

White rice was washed twice with twice the amount of water, the water used for washing was collected to prepare rice washing water, the prepared rice washing water was centrifuged, and the precipitate was purified with a 0.2% mass concentration sodium hydroxide aqueous solution, neutralized (pH 7.0) with a 1 N hydrochloric acid solution, washed with distilled water, and the precipitate was dried at room temperature to prepare washed water purified starch.

<Example 5> Manufacturing of OSA from refined white rice starch

120 mL of distilled water was added to 50 g of the white rice refined starch manufactured through the above Example 1, and then 1 N NaOH was used to maintain the pH at 8.5, and OSA solution was added to 3% of the starch weight, and after 6 hours of reaction, the solution was neutralized to pH 7.0 using 1 N HCl, and precipitated in a centrifuge at a speed of 5,000 rpm for 10 minutes, and then washed with distilled water and dried with hot air to manufacture starch. (White rice refined starch-OSA)

<Example 6> Manufacturing of OSA from purified starch using washing water

The same procedure as in Example 5 was followed, but starch was manufactured using the purified starch from the washing water manufactured through Example 2. (Refined starch from washing water-OSA)

<Example 7> Manufacturing of OSA from precipitated powder of washing water

The same procedure as in Example 5 was followed, but starch was manufactured using the purified starch from the washing water produced in Example 3. (Washing water precipitated powder-OSA)

<Example 8> Manufacturing of OSA concentrated powder from washing water

The same procedure as in Example 5 was followed, but starch was manufactured using the purified starch from the washing water produced in Example 4. (Concentrated washing water powder-OSA)

<Example 9> Manufacturing of annealed starch (40°C)

Annealed starch (40°C) was produced by annealing 50 g of the purified starch produced in Example 3 above at a temperature of 40°C for 24 hours.

<Example 10> Manufacturing of annealed starch (50°C)

50 g of the purified starch produced in Example 3 above was annealed at 50°C for 24 hours to produce annealed starch (50°C).

<Example 11> Manufacturing of annealed OSA starch (40°C)

120 mL of distilled water was added to 50 g of the purified starch manufactured through the above Example 3, and then annealed at a temperature of 40°C for 24 hours. The annealed mixture was maintained at pH 8.5 using 1 N NaOH, and an OSA solution was added to an amount of 3% of the starch weight, and after 6 hours of reaction, the mixture was neutralized to pH 7.0 using 1 N HCl, and precipitated using a centrifuge at a speed of 5,000 rpm for 10 minutes, washed with distilled water, and dried with hot air to manufacture starch. {Annealed OSA starch (40°C)}

<Example 12> Manufacturing of annealed OSA starch (50°C)

The same procedure as in Example 11 was followed, but starch was manufactured by annealing at 50°C. {Annealed OSA starch (50°C)}

The properties of the starch manufactured through the above Examples 1 to 12 were measured and are shown below.

*Color measurement of washing powder and refined starch

The color of the powder and refined starch separated from the washing water was measured using a spectrophotometer (CM-5, Minolta, Japan) in terms of lightness (L), redness (a), and yellowness (b), and is shown in Table 1 and Figure 3 below.

<Table 1>

As shown in Table 1 above and Fig. 3 below, the L, a, and b values of white rice refined starch, washed water refined starch, washed water precipitate powder, and washed water concentrated powder were 91.56 to 99.44, 0.16 to 0.53, and 1.02 to 10.69, respectively, when the color of white rice and rice washed water samples was measured. The higher the degree of purification of the sample, the higher the brightness and the whiter the color appeared, and the lower the degree of purification, the higher the yellowness.

*General composition and starch content of powder and starch separated from white rice and washed water

The general composition of starch purified from white rice and washing water was analyzed for ash content, crude protein, and crude fat according to AACCI (2012). Ash content was measured by direct ash method at 550℃, crude protein was analyzed using an analyzer using the Kjeldahl method, and crude fat was analyzed using an automatic extraction device using the Soxhlet extraction method. The total starch content of the sample separated from white rice and washing water was analyzed using a total starch analysis kit (Megazymes Pty) at 100 mg (db) of starch, and is shown in Table 2 below.

<Table 2>

As shown in Table 2 above, in order to confirm the possibility of utilizing rice washing water as a food material, the powder and starch were separated from the washing water, and the characteristics were compared with the starch separated from white rice. The unrefined washing water precipitate powder contains rice bran attached to the surface of the grains and soluble substances of white rice during the milling process, the washing water refined starch is starch obtained by alkali refining the washing water precipitate powder, and the white rice refined starch is starch obtained by alkali refining white rice. The general components of each sample were as shown in Table 1 above: moisture content 8.56~11.17%, ash 0.66~12.02%, crude protein 0.50~31.91%, crude lipid 0.10~10.84%, and total starch 63.19~93.74%. Compared to white rice refined starch and washed water refined starch, the washed water precipitate powder and concentrated powder had higher crude protein, crude lipid, and ash contents and lower total starch contents. Wash water refined starch had higher protein content and lower total starch content than white rice refined starch.

*Physicochemical properties

The water binding capacity of the sample separated from white rice and washing water and OSA starch was measured according to the method of Medcalf DG & Gilles KA (1965). 20 mL of distilled water was added to 0.5 g (db) of starch, stirred at room temperature for 1 hour, and centrifuged at 5,000 rpm for 30 minutes. The supernatant was removed, and the weight of the sediment was measured, and the water binding capacity (%) was calculated from the weight ratio with the original sample.

Swelling capacity and solubility were measured at 80℃. 0.5 g (db) of starch and 20 mL of distilled water were placed in a centrifuge tube, stirred at 80℃ for 30 minutes, cooled in ice water, and centrifuged at 8,000 rpm for 30 minutes. The dry weight of the supernatant and the weight of the sediment were measured to calculate the swelling capacity and solubility.

<Table 3>

As shown in Table 3 above, the water-binding capacity, swelling power, and solubility of the powder and starch separated from white rice and washing water and the OSA starch manufactured with the samples were 221.69–450.48%, 5.37–38.91, and 4.73–20.92%, respectively. Compared to white rice refined starch, the washed water refined starch showed a very high water-binding capacity of 432.59%, and the water-binding capacity of the unrefined powder washed water precipitated powder and washed water concentrated powder significantly decreased compared to the starch separated from the washed water. The samples manufactured by OSA esterification showed a similar tendency to the starches that were not treated with OSA, and it could be seen that the water-binding capacity of the refined starches, white rice refined starch-OSA and washed water refined starch-OSA, increased.

As a result of measuring the swelling power of starch and OSA starch, the starch and powder without OSA treatment had a significantly higher swelling power of washed water refined starch than white rice refined starch at 16.97%, similar to the results of water-binding capacity, and the swelling power of the washed water precipitated powder and concentrated powder significantly decreased compared to the washed water refined starch. When treated with OSA, the swelling power increased compared to the untreated group, and in particular, white rice refined starch-OSA increased the most compared to the untreated group, showing a higher value than the washed water refined starch-OSA. Solubility showed a similar trend to the water-binding capacity in the untreated and OSA treated groups.

In the present invention, when it was observed that starch purified from white rice and starch purified from washing water had differences in water binding capacity, swelling capacity, and solubility, it was presumed that starch in the endosperm portion and starch transferred from rice bran and the surface of white rice into the washing water had differences in particle size and structure. The reason for the difference in characteristics between starch purified from washing water and unrefined powder is that proteins, lipids, ash, etc. derived from washing water inhibit hydration and swelling of starch particles.

*Measurement of gelatinization properties by rapid viscosity meter

The viscosity change of starch and OSA starch gelatin solution according to temperature was measured using a rapid viscosity meter (RVA 4500, Perten, H The viscosity was measured using a gelatinization initiation temperature (℃), peak time (min), peak viscosity (P), trough viscosity (T), final viscosity (F), setback viscosity (FT), and breakdown viscosity (PT) were measured. The sample (3 g, based on 12% moisture content) was well dispersed in 25 mL of distilled water in an aluminum container, and the viscosity was measured at 50°C for 1 minute, heated to 95°C for 3.12 minutes, maintained at 95°C for 2.92 minutes, cooled to 50°C for 3.97 minutes, and maintained at 50°C for 2 minutes. From the measured data, the gelatinization initiation temperature (℃), peak time (min), peak viscosity (P), trough viscosity (T), final viscosity (F), setback viscosity (FT), and breakdown viscosity (PT) were obtained.

<Table 4>

As shown in Table 4 above, the gelatinization characteristics of the starch and powder separated from the washing water were measured using a rapid viscosity analyzer (RVA). The gelatinization characteristics of the refined starch separated from white rice were analyzed in terms of gelatinization initiation temperature, peak time, highest viscosity, lowest viscosity, final viscosity, settling viscosity, and drop-off viscosity, and were 74.08℃, 6.10 min, 3645 cP, 2643 cP, 4268 cP, 1626 cP, and 1003 cP. The gelatinization initiation temperature of the refined starch in the washing water slightly increased, but the viscosity decreased. The gelatinization temperature and peak time of the washed water precipitated powder were 93.63℃ and 7.00 minutes, respectively, which increased the gelatinization temperature and peak time and maintained a higher viscosity than the washed water purified starch. However, the washed water concentrated powder did not have a measured gelatinization temperature and its peak time was 6.07 minutes, which did not show the general starch gelatinization pattern, suggesting that the starch was damaged during the concentration process.

White rice refined starch-OSA and washed water refined starch-OSA manufactured from refined starch showed decreased gelatinization temperature and peak time compared to the untreated sample, but increased viscosity in both samples. Washed water precipitate powder-OSA showed a gelatinization pattern similar to the untreated group, and washed water concentrated powder-OSA showed a decreased viscosity compared to the untreated group.

*OSA substitution degree measurement

The degree of substitution of octenyl succinyl groups in OSA starch and powder was measured by the following method. 5 g of starch was placed in a triangular flask, 50 mL of distilled water was added, and mixed well. Then, 25 mL of 0.5 N NaOH solution was added. After stirring for 24 hours at room temperature using a magnetic bar, the substituted octenyl succinic acid reacted with NaOH, and the remaining amount of alkali was titrated with 0.5 N HCl to calculate the degree of substitution.

*Oil absorption capacity

To measure the retention capacity, 0.5 g of OSA starch and 15 mL of canola oil were mixed for 30 seconds using a vortex mixer, allowed to settle for 30 minutes, and centrifuged at 2730×g for 20 minutes. The supernatant was discarded, and the weight of the sediment was measured. The retention capacity was then calculated using the following equation.

Oil absorption capacity (%) = [Precipitated starch weight (g) - Initial starch weight (g)] × 100 / Starch weight (g)

<Table 5>

As shown in Table 5 above, the OSA substitution degree was measured after manufacturing OSA starch from the sample separated from the washing water, and the result was 0.014~0.088, and the three types of OSA starches manufactured from washing water starch and powder had higher substitution degrees than white rice refined starch-OSA. In particular, the washing water concentrated powder, which was made by concentrating the washing water and turning it into powder, showed the highest value of OSA substitution degree.

The results of measuring the retention capacity of starch without OSA treatment and OSA starch were 110.07~129.09%. In the case of no OSA treatment, the retention capacity of the washed water precipitated powder and concentrated powder separated from the washed water was higher than that of the white rice refined starch separated from the white rice. The washed water precipitated powder and concentrated powder were measured to have a higher lipid content than the other samples, and it was determined that the fat-soluble components contained therein had an effect. In addition, in the case of the OSA starch manufactured with each sample, the retention capacity increased by the OSA treatment, and it was determined that the OSA starch manufactured with the washed water sample has a high possibility of being utilized as an emulsifying stabilizer.

*Manufacture of emulsion containing OSA starch manufactured from detergent powder and detergent starch

The emulsion was prepared by mixing 50 g of canola oil and 50 g of continuous phase. The 50 g of continuous phase consisted of 1 g of washed water powder or starch, 0.02 g of xanthan gum, 0.01 g of sodium azide, and 48.97 g of water. The OSA starch was dispersed in advance at 50°C, and the xanthan gum was homogenized by stirring for 48 hours. The canola oil and continuous phase were mixed, homogenized with a high-speed homogenizer for 1 to 3 minutes, and then sonicated with a sonicator at amplitude 40% for 1 minute to prepare an emulsion.

-Measurement of viscosity and stability of emulsion

The viscosity of the emulsion was measured using a Brookfield viscometer, and the stability was investigated by measuring the volume separated while filling and storing the emulsion in a 10 mL graduated cylinder.

Creaming Index (%) = H _C / H _E × 100

H _C = volume of the lower separated part

H _E = total volume of emulsion

<Table 6>

As shown in Table 6 above, the viscosity of the emulsion manufactured from the washed water powder and the washed water starch, and the annealed OSA starch was measured to be 71.39 to 381.52 cP. The stability of the emulsion was measured while storing it at room temperature for 21 days, and the result was expressed as a creaming index, as shown in Figure 4 below. In the case of the starch separated from the kernels, 29% was separated 2 hours after the emulsion was manufactured, but the starch separated from the washed water was gradually separated after 2 days and about 13% was separated after 21 days. When the emulsion was manufactured by manufacturing OSA with the washed water refined starch, it was not separated at all until 21 days. In the case of the annealing treatment, about 9% was separated until 21 days, but the emulsion was not separated when the annealing treatment and OSA treatment were performed together. Therefore, it can be seen that the starch separated from the washing water has increased emulsification stability compared to the starch separated from white rice, and that the emulsification stability is greatly increased when the OSA starch is manufactured by simultaneously performing annealing treatment with the OSA starch.

*Manufacturing of dumpling skin for steamed dumplings

Dumpling skin for steamed dumplings was made by mixing 68% tapioca starch, 32% potato starch, sweetener, and salt, adding 95℃ water, and kneading the dough. Among these, a powder was manufactured by replacing some of the tapioca starch with alpha-micron powder, washed starch, and modified starch, and compared with the existing dumpling skin.

<Table 7>

As shown in Table 7 above, the results of measuring the cold-thaw stability of dumpling skins for steamed dumplings containing washed water starch and OSA starch showed that 4.6% of the tapioca starch in the existing dumpling skin powder was replaced with washed water starch and starch that had undergone both annealing and OSA substitution to manufacture dumpling skin powder, and the cold-thaw stability was measured by repeating the cold-thaw cycle 1 to 5 times. As shown in Fig. 5 below, there was no significant difference between the samples up to the second cold-thaw cycle, but the difference in moisture content increased from the third cycle. As a result of repeating the cold-thaw cycle 5 times, when washed water starch was replaced, the moisture content decreased by 35.4 to 50.1% compared to the existing dumpling skin, and when annealing and OSA were combined, it decreased by 14.4 to 25.2%. Although starch itself separated from the washing water is effective in improving freeze-thaw stability, it was found that freeze-thaw stability can be significantly improved when starch is manufactured by simultaneously performing annealing treatment and OSA treatment and then added to the dumpling skin.

*Measurement of cold-thaw stability of dumpling skins for steamed dumplings containing cleansing water powder and OSA starch

A 6% concentration suspension was made with washing powder, starch, OSA starch, and dumpling skin powder made from these, and a gelatin solution was made by stirring and heating, placing 1 g each in a microtube, cooling to room temperature, and storing at 4°C for 24 hours. It was frozen in a -20°C freezer for 20 hours, thawed at room temperature for 4 hours, and centrifuged in a centrifuge at 3,000 rpm for 10 minutes. The separated water was discarded, and the weight of the remaining gel was measured to calculate the water content. The freeze-thaw cycle was repeated 1, 2, 3, 4, and 5 times, and the amount of water separated at that time was measured to compare the water content.

- Measuring the physical properties of dumpling skins for steamed dumplings containing cleansing water powder and OSA starch

The dumpling skin powder for steamed dumplings containing washing water powder, starch, and OSA starch manufactured from the mixture was mixed, 95℃ hot water was poured in, kneaded, and placed in a steamer for 30 minutes to manufacture the dumpling skin, which was then shaped into 1.0×1.0×1.0 cm and the texture was measured using TA.

<Table 8>

As shown in Table 8 above, the dumpling skins for steamed dumplings were manufactured by adding a washing water sample, and the results of measuring the physical properties were as follows. The dumpling skins with the addition of washing water, refined starch, precipitated powder, and annealed OSA starch showed increased hardness and adhesiveness, slightly decreased cohesiveness, and a tendency for increased chewiness compared to the existing dumpling skins.

The dumpling skin for steamed dumplings was quickly frozen at -70℃ and then stored in the freezer, similar to the distribution process for steamed dumplings, and its physical properties were measured by reheating it in a microwave oven in the same way as eating steamed dumplings. As shown in Table 8, the hardness of the existing dumpling skin increased by about 3 times, and depending on the additive, the increase in hardness increased up to 6 times, but when the washed water precipitated powder and annealed OSA starch were added, the hardness was maintained or decreased. Therefore, it is judged that the washed water powder and annealed OSA starch can be utilized as additives that can improve the texture of frozen steamed dumplings.

Therefore, the method for manufacturing starch using rice washing water according to the present invention provides starch with significantly improved emulsification stability and freeze-thaw stability.

S101; Starch recovery stage
S103; Distilled water mixing stage
S104; Annealing step
S105; Succinic acid mixing stage
S107 ; Neutralization stage
S109; Centrifugation step
S111; Washing and drying stage

Claims (7)

Starch recovery step for recovering starch from rice washing water;
A distilled water mixing step of mixing distilled water into the starch recovered through the above starch recovery step;
A succinic acid mixing step of mixing anhydrous octenyl succinic acid and sodium hydroxide into the mixture prepared through the distilled water mixing step;
A neutralization step for neutralizing the mixture manufactured through the above succinic acid mixing step;
A centrifugation step for centrifuging the mixture neutralized through the above neutralization step; and
A method for manufacturing starch using rice washing water, characterized in that it comprises a washing and drying step of washing the starch separated through the centrifugal separation step and then drying it with hot air.
In claim 1,
Between the distilled water mixing step and the succinic acid mixing step, an annealing step is further performed to anneal the mixture manufactured through the distilled water mixing step.
A method for manufacturing starch using rice washing water, characterized in that the above annealing step is performed at a temperature of 40 to 50°C for 20 to 30 hours.
In claim 1,
The above starch recovery step is a method for manufacturing starch using rice washing water, characterized in that it comprises centrifuging rice washing water, recovering a precipitate, purifying the recovered precipitate with a sodium hydroxide aqueous solution having a mass concentration of 0.2%, neutralizing it with a 1 N hydrochloric acid solution, washing it, and drying it.
In claim 1,
A method for manufacturing starch using rice washing water, characterized in that the distilled water mixing step is performed by mixing 180 to 300 parts by weight of distilled water with 100 parts by weight of starch manufactured through the starch recovery step.
In claim 1,
A method for manufacturing starch using rice washing water, characterized in that the above succinic acid mixing step is performed by mixing 2 to 4 parts by weight of anhydrous octenyl succinic acid relative to 100 parts by weight of starch contained in the mixture manufactured through the above distilled water mixing step, mixing sodium hydroxide, and reacting the mixture for 5 to 7 hours while maintaining the pH of the mixture at 8 to 9.
In claim 1,
A method for manufacturing starch using rice washing water, characterized in that the neutralization step is performed by mixing 1N hydrochloric acid into the mixture manufactured through the succinic acid mixing step to adjust the pH of the mixture to 6.9 to 7.1.
In claim 1,
A method for manufacturing starch using rice washing water, characterized in that the centrifugation step is performed at a speed of 4,500 to 5,500 rpm for 8 to 12 minutes.